dumb wiring question

[slag]

I have an over the sink light that is just 2 wires going to a switch. When the switch is on, the lights are on, and vice versa. It's a simple circuit, connect it, and the lights have power, take it away, and they dont. I bought one of these to install at the switch and I don't think I can do it.
https://www.amazon.com/gp/product/B01N41DK1V/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

It requires a pair of wires coming in and going out and I only have one pair total, right, so this would have to be installed wherever there are the two pairs of wires going to the lights, probably up at the ceiling near one of the lights. This is correct, right?

I can't think of a way to install it at the switch where it would work.

Here's the user guide.

https://www.itead.cc/blog/user-guide-for-sonoff-slampher

 

[dave_the_nerd]

Photos of switch/wiring?

If this is household, you should have a hot and a ground. They're usually color coded. The switch may only be switching (connecting/disconnecting) the hot, but the ground shoudl be there somewhere.

 

[slag]

It should, but I think it's up at the fixtures. Not at home right now, but when I get there, I'll take and post photos.

 

[boomerang]

L and N refer to Load and Neutral.

The black wire is Load and the white wire is Neutral. If you have enough slack, the white wire can be cut and you have all the wires you need. When I say that, I am assuming that the white wire is continuous up to the fixture. If there is not enough slack, you can cut the white wire and pigtail both ends or put the device at the fixture where yes, you will have the wires you need.

I guess what I wonder is if it will fit in the box where the switch now resides or if it will have to go up at the fixture.

 

[slag]

L and N refer to Load and Neutral.

The black wire is Load and the white wire is Neutral. If you have enough slack, the white wire can be cut and you have all the wires you need. When I say that, I am assuming that the white wire is continuous up to the fixture. If there is not enough slack, you can cut the white wire and pigtail both ends or put the device at the fixture where yes, you will have the wires you need.

I guess what I wonder is if it will fit in the box where the switch now resides or if it will have to go up at the fixture.

Right, I get the concept of Load and Neutral, but this isn't like a regular light switch that has Load, Neutral, Ground coming in, going to a switch, and then a separate set of wiring going out to the fixture. This is literally 3 wires coming out of a hole in my cabinet base, up the inside of the cabinet, and going out on the side where it terminates at a switch. The black and white wires are hooked up to the switch and the bare copper is grounded out to the gang box.

So, I disconnected the wires going to the switch, attached them to the "input" side of the wireless sonoff switch, then hooked up a spare piece of romex to the outgoing side and hooked it up to the light switch. The only thing that happens when I turn the wireless switch on is the lights flicker every half second or so, but its not correct because the power coming in needs to complete the circuit and then give power to the lights, but theres no signal wire at the switch going to the lights, just a simple "complete the circuit" switch.

 

[Ken g6]

I think you'd need to run another wire, e.g. from an outlet, to provide power on the input side.

 

[Greenman]

First, lets get the nomenclature right. The black wire is generally the hot lead, the white wire is generally the neutral, the bare copper or green wire is the ground (I say generally because you never know what the last guy did. I've seen ground wires used as conductors). The ground isn't considered a conductor, it should only have current going through it if there is a fault in the appliance or the system.

The switch in this case is simply breaking a single hot wire. Whoever installed it just ran a single piece of romex from the fixture to the switch. The power comes out of the fixture box on the black conductor, goes to the switch, and returns to the fixture on the white wire. The white lead should have been marked with black tape to indicate that it was actually a hot wire. You don't have a neutral wire at the switch, so you can't connect a powered device to it.

Also note that in residential wiring the neutral wire should never be switched, though I have seen it done.

 

[slag]

First, lets get the nomenclature right. The black wire is generally the hot lead, the white wire is generally the neutral, the bare copper or green wire is the ground (I say generally because you never know what the last guy did. I've seen ground wires used as conductors). The ground isn't considered a conductor, it should only have current going through it if there is a fault in the appliance or the system.

The switch in this case is simply breaking a single hot wire. Whoever installed it just ran a single piece of romex from the fixture to the switch. The power comes out of the fixture box on the black conductor, goes to the switch, and returns to the fixture on the white wire. The white lead should have been marked with black tape to indicate that it was actually a hot wire. You don't have a neutral wire at the switch, so you can't connect a powered device to it.

Also note that in residential wiring the neutral wire should never be switched, though I have seen it done.

I agree with you, the existing physical switch is just an interrupt in the power line. I need to go up to the fixture to find the other wires. or find a google assistant compliant switch that can just turn on and off power remotely through google home.

 

[dullard]

The light needs load and neutral. But, the normal switch only needs to switch one of those wires (normally you would switch the load wire). The other wire is there, somewhere in the circuit, just they were cheap in wiring your switch and only ran the one wire that is absolutely necessary the extra few feet.

That smart switch however needs to switch a wire AND have power to read the Wi-Fi signal. Thus the smart switch needs both the load and the neutral in order to operate. You'll have to run the other wire to the Wi-Fi switch.

 

[Paperdoc]

Greenman and following have it right. In most applications, the wires in the cable are Black = Hot (Line), White = Neutral, and Bare = Ground. There should never be any current flowing in the Ground lead, so make no connections to it other than having it connected to the fixture mounting box.

A plain switch (such as you have in the box) needs no power. What is already installed is a normal way to do things. The power comes first to the light fixture mounting box, then a single 14/2 cable (14 gauge wires, 2 conductors plus bare Ground) is run to the switch mounting box, with Black connected to Black. But then the slightly-atypical connection is made to use the WHITE wire in that cable to bring the power back from the switch output to the Hot terminal of the light fixture; thus, that one White line is NOT a Neutral line, it is a switch output.

The Sonoff unit you bought has an extra requirement beyond those of a plain switch. It needs electrical power itself to run its electronics, so it needs access to BOTH a Hot and a Neutral connection. Right now your existing switch box does not have those leads coming to it, so that Sonoff unit cannot get power to work properly. To do this right, you will need to do some re-wiring to provide for those needs. NOTE!! Turn off ALL power to this circuit at the breaker box before opening and working!

The simplest way, which I have done, requires that you be able to add an extra cable from the lighting fixture box to the switch box. If you can do that, the straightforward version is to leave the original 14/2 cable in place and add one more just like it. In this arrangement, the old cable becomes solely the supply of Hot, Neutral and Ground to the switch box, and the new cable will serve as means of returning the switch Hot output to the light fixture, with all the Neutrals joined also.. DISconnect the White wire coming back from the old cable (from the switch) from the light fixture Hot terminal. There should already be a short White wire from the power source cable's White to the Neutral terminal of the light fixture. Now connect the White of the new cable with the White of the old cable, the White from the incoming power source, and the short White to the fixture. Connect the Black from the new cable only to the Hot terminal of the light fixture. Grounds for all three cables are twisted together and tied down to the box's Ground screw. Now at the Swtich box you will REPLACE the old switch with this Sonoff unit. That might be a problem because the unit may not fit the standard mounting box, but more on that later. The OLD cable must go to the Sonoff unit's INPUT terminals - Black to L, White to N. Its bare Ground twists with the other bare ground and they get screwed to the box's Ground screw at back. The Black of the NEW cable goes to the Sonoff's L OUTPUT terminal, and the new cable's White goes to the N Output.

When I have done this type of job, it has been easy for me to remove the original old 14/2 cable and install in its place a 14/3 cable that has an additional Red wire in it. Then you don't have an extra White wire to connect at both ends, nor is there a second bare Ground wire. The Black from the 14/3 cable is the power SUPPLY going from the fixture box's supply line to the switch box, and in your case would go to the Sonoff's INPUT L terminal. The RED in the cable goes to the Sonoff's L OUTPUT terminal to take power back to the fixture box, and there it is the one connected to the Hot terminal of the fixture. In the switch box, the incoming White goes to the Sonoff unit's N INPUT terminal, and there is nothing connected to the Sonoff's N Output terminal.

If the Sonoff unit does not fit your existing switch mounting box you might be able to adapt it to fit anyway. Be aware that, once this Sonoff unit replaces your old manual switch, it does NOT appear to have a manual switch button on it. So the ONLY way to switch that light on and off is by using the Wifi control signals that the Sonoff unit requires.

IF you want an additional manual switch in parallel with the Sonoff unit, so you can switch it on manually, you'll need moire installation work.

 

[jtworldwide3]

will the sonoff unit fit in the light box?

 

[stormkroe]

Without seeing a wiring diagram, I assume that the neutral connection is only there so the device itself can be powered without a battery. Hopefully it doesn't actually interrupt the neutral and hot, as it's never good practice to disconnect the neutral during normal operation. I would bet that if you had a neutral going IN to that box (say you had a 14/3 coming down from your light, N down on the white, constant power down on the red and back on the black) it would work just fine.

 

[slag]

Greenman and following have it right. In most applications, the wires in the cable are Black = Hot (Line), White = Neutral, and Bare = Ground. There should never be any current flowing in the Ground lead, so make no connections to it other than having it connected to the fixture mounting box.

A plain switch (such as you have in the box) needs no power. What is already installed is a normal way to do things. The power comes first to the light fixture mounting box, then a single 14/2 cable (14 gauge wires, 2 conductors plus bare Ground) is run to the switch mounting box, with Black connected to Black. But then the slightly-atypical connection is made to use the WHITE wire in that cable to bring the power back from the switch output to the Hot terminal of the light fixture; thus, that one White line is NOT a Neutral line, it is a switch output.

The Sonoff unit you bought has an extra requirement beyond those of a plain switch. It needs electrical power itself to run its electronics, so it needs access to BOTH a Hot and a Neutral connection. Right now your existing switch box does not have those leads coming to it, so that Sonoff unit cannot get power to work properly. To do this right, you will need to do some re-wiring to provide for those needs. NOTE!! Turn off ALL power to this circuit at the breaker box before opening and working!

The simplest way, which I have done, requires that you be able to add an extra cable from the lighting fixture box to the switch box. If you can do that, the straightforward version is to leave the original 14/2 cable in place and add one more just like it. In this arrangement, the old cable becomes solely the supply of Hot, Neutral and Ground to the switch box, and the new cable will serve as means of returning the switch Hot output to the light fixture, with all the Neutrals joined also.. DISconnect the White wire coming back from the old cable (from the switch) from the light fixture Hot terminal. There should already be a short White wire from the power source cable's White to the Neutral terminal of the light fixture. Now connect the White of the new cable with the White of the old cable, the White from the incoming power source, and the short White to the fixture. Connect the Black from the new cable only to the Hot terminal of the light fixture. Grounds for all three cables are twisted together and tied down to the box's Ground screw. Now at the Swtich box you will REPLACE the old switch with this Sonoff unit. That might be a problem because the unit may not fit the standard mounting box, but more on that later. The OLD cable must go to the Sonoff unit's INPUT terminals - Black to L, White to N. Its bare Ground twists with the other bare ground and they get screwed to the box's Ground screw at back. The Black of the NEW cable goes to the Sonoff's L OUTPUT terminal, and the new cable's White goes to the N Output.

When I have done this type of job, it has been easy for me to remove the original old 14/2 cable and install in its place a 14/3 cable that has an additional Red wire in it. Then you don't have an extra White wire to connect at both ends, nor is there a second bare Ground wire. The Black from the 14/3 cable is the power SUPPLY going from the fixture box's supply line to the switch box, and in your case would go to the Sonoff's INPUT L terminal. The RED in the cable goes to the Sonoff's L OUTPUT terminal to take power back to the fixture box, and there it is the one connected to the Hot terminal of the fixture. In the switch box, the incoming White goes to the Sonoff unit's N INPUT terminal, and there is nothing connected to the Sonoff's N Output terminal.

If the Sonoff unit does not fit your existing switch mounting box you might be able to adapt it to fit anyway. Be aware that, once this Sonoff unit replaces your old manual switch, it does NOT appear to have a manual switch button on it. So the ONLY way to switch that light on and off is by using the Wifi control signals that the Sonoff unit requires.

IF you want an additional manual switch in parallel with the Sonoff unit, so you can switch it on manually, you'll need moire installation work.

I read a bit and got bored. There's no way to run a wire down from the fixture to the switch. This is an island in the middle of an open kitchen and what you call "the simplest way" is going to be not simple at all and more work than I want to put into it. The sonoff switch was $7.00. If I have to spend more than that on Romex, it's not going to happen, and I'd need at least a hundred feet if not more of wiring to do this due to the position of the island and switch.

 

[slag]

will the sonoff unit fit in the light box?

I dont know. Might be more work than I want to mess with. Seriously, why couldn't they wire this like normal people would.. GAH

 

[NL5]

I dont know. Might be more work than I want to mess with. Seriously, why couldn't they wire this like normal people would.. GAH

Actually, it was common practice to wire switches like that. The NEC does not allow that anymore, specifically because of the kind of device you are trying to install. You might check and see if they make a version that doesn't require a neutral. They are still available AFAIK. (powered devices) They put a tiny amount of current on the ground, and were previously allowed. The reason for the code change was that too many of them were installed a single dwelling , and put a more significant amount of current on the ground.

Edit - here is one with a switch, dimmer, and wifi. No neutral required.

https://www.amazon.com/Base-Switch-wireless-function-required/dp/B01LWOTR2M

 

[slag]

Actually, it was common practice to wire switches like that. The NEC does not allow that anymore, specifically because of the kind of device you are trying to install. You might check and see if they make a version that doesn't require a neutral. They are still available AFAIK. (powered devices) They put a tiny amount of current on the ground, and were previously allowed. The reason for the code change was that too many of them were installed a single dwelling , and put a more significant amount of current on the ground.

Edit - here is one with a switch, dimmer, and wifi. No neutral required.

https://www.amazon.com/Base-Switch-wireless-function-required/dp/B01LWOTR2M

When was it common?> My house is 9 years old.

 

[NL5]

When was it common?> My house is 9 years old.

IIRC, it changed in the 2011 NEC. Depending on your jurisdiction, it may not even be adopted yet.

 

[Micrornd]

If you have room in the lighting fixture this will work.
https://ibb.co/by6ueb
Your existing switch will need to be left in the "on" position for the remote unit to work.
If the existing switch is turned "off", the remote will not work and the light will not come on at all.

 

[Greenman]

I read a bit and got bored. There's no way to run a wire down from the fixture to the switch. This is an island in the middle of an open kitchen and what you call "the simplest way" is going to be not simple at all and more work than I want to put into it. The sonoff switch was $7.00. If I have to spend more than that on Romex, it's not going to happen, and I'd need at least a hundred feet if not more of wiring to do this due to the position of the island and switch.

There isn't a regular outlet in the island you could snag a neutral from? There should be, as the island outlet is code requirement.

 

[slag]

There isn't a regular outlet in the island you could snag a neutral from? There should be, as the island outlet is code requirement.

Actually, there probably is. The garbage disposal has a neutral drop and I installed a new gang box/outlet off it a few years ago when I put in the dishwasher. It's about 6 feet away after I have to route the wiring and get it up out of the way.

 

[stormkroe]

Actually, there probably is. The garbage disposal has a neutral drop and I installed a new gang box/outlet off it a few years ago when I put in the dishwasher. It's about 6 feet away after I have to route the wiring and get it up out of the way.

It's against code to steal a neutral from a different circuit, just and FYI.

 

[NL5]

It's against code to steal a neutral from a different circuit, just and FYI.

This is true. You could potentially overload the neutral, although improbable with just that switch. If you do pull the neutral from an outlet, I would pull power with it, and rewire the light so it is running off the outlet circuit. That way it will be properly protected by the ocpd (breaker).

Or, just get the version that doesn't require a neutral. Much easier IMHO.

 

[stormkroe]

This is true. You could potentially overload the neutral, although improbable with just that switch. If you do pull the neutral from an outlet, I would pull power with it, and rewire the light so it is running off the outlet circuit. That way it will be properly protected by the ocpd (breaker).

Or, just get the version that doesn't require a neutral. Much easier IMHO.

Apart form overload potential, which is admittedly pretty small in this instance, it creates a parallel neutral pathway that is a big no-no. I agree that, while it's also against kitchen receptacle codes to add a light to the circuit, it's a much lesser evil that parallel neutral pathways.

 

[NL5]

Apart form overload potential, which is admittedly pretty small in this instance, it creates a parallel neutral pathway that is a big no-no. I agree that, while it's also against kitchen receptacle codes to add a light to the circuit, it's a much lesser evil that parallel neutral pathways.

That's why I keep suggesting getting a non-nuetral version of his device. Everything would be easier and better than the alternatives.

 

[slag]

Maybe i missed it, but i didn't see the non neutral version..